The purpose of this application is to request partial support of the travel expenses for invited speakers and Session Chairpersons to the 43rd Gordon Research Conference on Cancer -- one of the oldest of the Gordon Conferences. For 1991 the meeting is being organized around the theme of "The Molecular and Cellular Basis of Tumor-Host Tissue Interactions" and will take place August 11-16 at Salve-Regina College in Newport, R.I. The growth, spread, and treatment of cancer is known to be significantly influenced by the local environment in which tumors are found. The aim of the 1991 Conference is to provide a critical forum to consider the latest research developments which provide an understanding of the molecular and cellular basis of such tumor-host interactions and their possible clinical applications. To this end, it has been organized around nine oral sessions and three poster sessions. The oral sessions have been arranged so as to consider a diverse, but inter-related set of problems relevant to the tumor-host relationship. They include: (1) tumor angiogenesis and its inhibition; (2) growth factor and hormonal interactions; (3) cell-cell interactions; (4) cell-matrix interactions-I; (5) cell-matrix interactions-II; (6) microenvironmental modulation of drug resistance; (7) immune interactions; (8) the future: new directions. In addition, one session will consist of six presentations by registered participants selected from the abstracts/posters submitted. We expect the 1991 Gordon Research Conference on Cancer will provide a lively and pivotal forum for discussion of a topic which has far-reaching implications for many aspects of tumor biology and clinical oncology, but which has not been addressed in so focussed a manner in previous cancer research meetings.